Apparatus for smelting ores yielding a volatile metal.



W. McA. JOHNSON.

APPARATUS FOR SMELTING ORES YIELDING A VOLATILE METAL.

APPLICATION FILED NOV. 9, 1906.

Patented July 12, 1910.

wrceaagax UNITED STATES PATENT OFFICE.

WOOLSEY McA. JOHNSON, OF HARTFORD, CONNECTICUT, ASSIGNOR TO THE CONTIN-UOUS ZINC FURNACE COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OFCONNECTICUT.

APPARATUSFOR SMELTING ORES YIELDING A VOLATILE METAL.

T 0 all whom it may concern:

Be it known that I, ooLsnr MoA. JOHN- SON, a citizen of the UnitedStates, residing at Hartford, in the county of Hartford and State ofConnecticut, have invented certain new and useful l'mproven'ients inApparatus for Smelling Ores Yielding a Volatile Metal, of which thefollowing is a specification.

This invention is an apparatus for smelting ores yielding a volatilemetal, said apparatus comprising, in operative connection, an electricsmelting furnace, a reducer for the volatile reaction productstherefrom, and a condenser.

In the preferred embodiment of the in vention the electric furnace is soconstructed as to facilitate the production and removal of the fluidslag, and the reducer comprises a chamber for containing a body of coke,coal or other carbonaceous material, provided with electrodes in contactwith said body.

For a full understanding of the invention reference is made to theaccompanying drawing, showing in central vertical section a preferredform of apparatus embodying the invention.

Referring to said drawing, 1 represents an electric furnace, shown ascomprising a smelting chamber 2 formed of or interiorly lined with asuitable refractory material, 8, 3 representing carbon electrodessupported in the upper part of the furnace and terminating above thelevel of a slag tap 4. The electrodes 3, 8 are preferably of the samepolarity, the opposing electrode 5 being embedded in the hearth of thefurnace, in electrical contact with a conductive plate or bar 6. 7 is ahopper for the introduction of the charge 8, and 9 is a tap for theremoval of non-volatile metals or matte 10. It will be noted that inthis form of furnace the current traverses the bath of slag 11,superheating the same and rendering tapping easy.

The volatile reaction products pass through the outlet- 12 and thencethrough a column 13 of coke or coal contained in a chamber 14 andadapted to be heated by an electric current passing between upper andlower ring electrodes 15, 16, set in the walls of the reducing chamber.The reducing Specification of Letters Patent.

Application filed November 9, 1906. Serial No. 342,666.

Patented July 12', 1910.

. coal, normally closed by a cover 18 set in a sand or other seal 19.

20 IS a d scharge gate for coke and ash, the coke being replaced fromtime to time as may be necessary for maintaining substantially constantelectrical conditions.

From the reducing chamber 14 the vapors, freed from carbon dioxid,aqueous vapor and other compounds capable of oxidizing zinc, pass to asuitable condenser 21, shown as provided with water-cooled partialpartitions 22 constructed to direct the vapors in a tortuous path.

23 is the outlet for non-condensing gases, and 24: the metal tap.

In the smelting of zinc ores in the manner heretofore practiced the orehas usually been mixed with an excess of carbon above the amountnecessary for the reduction, the purpose of such excess being two-fold,viz. (1) to insure a highly reductive charge or one capable of effectingthe substantial reduction of carbon dioxid, aqueous vapor, and otherreaction products which are capable of oxidizing zinc at or near itstemperature of condensation;-and (2) to insure the presence of carbon inthe residue, whereby the same is rendered pulverulent and infusible, anyslag fusible at the temperature of reduction being absorbed or retainedby the carbon. This is of the utmost importance in externally firedfurnaces, for a fluid slag or matte in contact with externally firedfireclay retorts would quickly destroy them.

In the use of my apparatus I prefer to incorporate with the charge onlysuch proportion of carbon as is necessary for the reduction of themetallic constituents thereof,

producing thereby an easily fusible slag REISSUED metal volatilized, itis necessary that the operation should proceed under certain definite'conditions: 1. The smelting should be conducted in an electric furnace:as above stated the production of fluid slags would be destructive toexternally fired retorts, and any method other than retortingwouldrequire the introduction of such quantities of air in the form of ablast that it would be impossible to secure efiicient condensation. 2.The mineral components of the char e which enter into. the slag shouldprefera%ly be so proportioned as to yield a slag fusible at 1100 to 1175(1., such slag being superheated at the working tern erature of thefurnace, 12501300 0., a therefore readily tapped. 3. The gases derivedfrom a charge of the character described are necessarily oxidizing incharacter and are passed through a body of porous carbonaceous materialat a high temperature, and preferably under conditions of maximumreductivity secured by electric heating.

It is not essential that the body of carbon employed for reducingvolatile reaction products should be electrically heated, but suchelectrical heating possesses peculiar ad- I vantages in this relation,in that in addition to the high average temperatures, above thecondensing point of zinc, which are readily secured, there are presenteda multitude of points of extremely high temperature, viz. the points oflocal arcing. At such points the vapor of carbon is present and thecarbon is in a condition of maximum reductivity. I have found that bythis means I am able to secure a more perfect reduction of the volatileproducts than could be obtained by operating at a temperature of 1020 to1150 0. upon a charge containing a large excess of carbon.

I am aware that it has been proposed to pass zinc vapors from a retortor furnace operating on a charge having an excess of carbon through abody of heated carbon, and I do not claim such procedure. Such method mabe eflicient as regards recovery of the meta but is necessarilyuneconomical because the working is necessarlly mtermittent.

I am further aware that it has been proposed to secure the advantages ofa continucarbon in the charge, the zinc vapors being thereafter directlycondensed. In this case such economics as result from continuousoperation are secured, but the process is necessarily inefiicientanduncommercial by reason of the loss of zinc by oxidation by carbondioxid.

I believe myself to be the first to recognize that a continuousoperation may be combined with a high degree of working efiiciency byelectrically smelting a charge f the furnace, a slag adapted to yield afusible slag, and passing the vapors therefrom through a body of carbonat a reducing temperature, and preferably at the temperature of maximumreductivity, that is to say at a temperature at.

which carbon vapors are present.

I claim:

1.. Apparatus for smelting ores yielding a volatile metal, comprising,1n operative connection, an electric smelting furnace, a porous body ofcarbonaceous material, a condenser, and means for heating said body ofcarbonaceous material, substantially as described.

2. Apparatus for smelting ores yielding a volatile metal, comprising, inoperative connection, an electric smelting furnace, a porous body ofcarbonaceous material, a condenser, and electrodes disposed in contactwith said body of carbonaceous material,

substantially as described.

3. Apparatus for smelting ores yielding a volatile metal, comprising, inoperative connection, an electric smelting furnace, a reducing chambercontaining a carbonaceous material, a condenser, and ring electrodesdisposed in said reducin chamber near opposite ends thereof, suistantially as described.

4. Apparatus for smelting ores yielding -a volatile metal, comprising,in operative connection, an electric smelting furnace, a reducingchamber containing a carbonaceous material and having charging anddischarging a ertures, a condenser, and ring electrodes isposed in saidreducing chamber near opposite ends thereof, substantially as described.

5. In apparatus for smelting ores yielding a volatile metal, an electricfurnace comprising a closed furnace chamber, electrodes in the upper andlower portions of the same, a slag tap intermediate said electrodeswhereby the current is caused to traverse a bath of slag means forcollecting and condensing the volatile metal evolved in said apparatus,substantially as described.

6. In apparatus for smelting ores yielding a volatile metal, an electricfurnace comprising a closed furnace chamber, electrodes in the upper andlower portions of the same, a charging aperture in the upper portion oftap intermediate said electrodes whereby the current is caused totraverse a bath of slag means for collectin and condensing the volatilemetal evolved in said apparatus, substantially as described.

In testimony whereof, I afiix my signature in presence of two witnesses.

WOOLSEY McA. JOHNSON.

Witnesses:

A. H. GRAHAM, HARRY L. HILL-MAUI.

